1. Field of the Invention
The present invention relates to a technology of patterning a resin film or metal film on a multilayer thin film of a flat panel display (FPD) or the like. More particularly, the present invention relates to a laser processing apparatus and a laser processing method, and a debris collection mechanism and a debris collection method, which are intended to remove and collect debris generated during laser processing by ablation, thermofusion or their mixed action by irradiating a surface of an object with laser light, and to a method for producing a display panel.
2. Description of the Related Art
In a process for producing a flat panel display such as a liquid crystal panel, many thin films such as resin films or metal films are superposed on a glass substrate to form a TFT (thin film transistor) substrate, a CF (color filter) substrate or the like. Many photolithography processes are used for patterning and etching such a multilayer substrate.
In a photolithography process, a resin film or metal film is vacuum deposited on a substrate such as a glass, plastic or silicon wafer substrate; a resist layer is formed on the film; and the resist layer is exposed by irradiation with light through a photomask having a predetermined pattern. Then, the photomask pattern is transferred to the resist layer by development and post-baking; areas not covered with the resist in the resin film or metal film are removed by wet etching; and finally the remaining resist layer is removed to obtain a desired pattern of the resin film or metal film.
However, the photolithography process needs a large apparatus such as a coater/developer and is therefore disadvantageous in terms of equipment investment and footprint. The process is also disadvantageous in terms of environmental protection, because a large amount of a chemical such as a developer is used. In this situation, Japanese Unexamined Patent Application Publication No. 2004-153171 proposes a technology of directly processing a thin film such as a resin film or metal film using laser light for omitting the photolithography process and simplifying the production process, for example.
In performing laser processing, it may be generally necessary to collect a substance called debris. Debris is a product from a material by absorption and reaction of laser light or fine particles (waste) from a material. They float and diffuse in the air and are reattached to a substrate. In particular, the reaction product attached to the substrate is solidified due to deprivation of heat and may not even be removed by physical washing using a brush or the like. Therefore, desired processing quality and processing accuracy may not be obtained and product failure occurs. In the field of fine process for a flat panel display such as a liquid crystal panel, such a reattached substance is particles (waste) causing 100% failure. Therefore, a technology of collecting debris may be necessary.
For example, Japanese Unexamined Patent Application Publication No. 10-99978 proposes a debris collection method including providing a fluid delivery apparatus ejecting gas to a surface near a processed region and a fluid suction duct opposite to the fluid delivery apparatus to blow debris off the processed region and suck and remove the debris at the same time (Method 1).
As known, it is effective to blow assist gas to an object while irradiating the object with laser light in order to reduce an amount of debris generated. For example, Japanese Unexamined Patent Application Publication No. 9-192870 proposes a method including providing an internal nozzle on a laser processing head and an external nozzle surrounding a periphery of the internal nozzle to eject assist gas to a processed region from the internal nozzle and suck the ejected assist gas using the external nozzle to exhaust debris (Method 2).
Known methods for controlling generation of debris itself include a method including preventing decomposition or reattachment of debris using predetermined atmospheric gas; and a method including processing an object under reduced pressure having a degree of vacuum of about 10 Pa (10−2 Torr), where it is possible to considerably reduce an amount of debris attached to and accumulated on the object.
Further, for example, Japanese Unexamined Patent Application Publication No. 2004-337947 proposes a laser processing method including providing a laser processing head outputting laser light to an object; and a nozzle mounted on a side of the laser processing head facing the object to irradiate the object with the laser light output from the laser processing head through the nozzle and allow the nozzle to suck debris generated near the object together with assist gas while spirally rotating the debris (Method 3).